Knife-grinding machine.



9 1 5 Mmn 0AM HM; S M DmL .mm P .BA Jmm n A Patented Aug. 11, 1914;

2 SHEETS-SHEET 1.

INVENTOR THE NORRIS PETERS C0,. PHOTO-LITHO. WASHINGTON, D. C.

J. P HEDSTROM.

KNIFE GRINDING MACHINE.

APPLICATION FILED JUNE 15, 1912.

1,106,560. Patented Aug. 11, 1914.

2 SHEETS-SHEET 2.

THE NORRIS PETERS (20., PHOTO-LITHO., WASHINGTONID. c,

nmrnn sra'rns PATENT curios.

JOHN P. HEDSTROM, OF BIG RAPIDS, IMICHIGAN.

KNIFE-GRINDING MACHINE.

To all whom it may concern Be it known'that I, J OHN P. HnDs'rRoM, a citizen of the United States, residing at Big Rapids, in the county of Mecosta and State of Michigan, have invented certain new and useful Improvements in Knife- Grinding Machines; and I do hereby declare the following to be a1full, clear, and eXact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

[his invention relates to knife grinding machines and pertains more particularly to that class of grinding machines commonly employed for sharpening planer knives and the like, in which the knife to be sharpened is mounted in a reciprocating carriage, the knife being passed back and forth endwise across the grinding faces of the wheel.

My improvement relates more especially to improved means by which the grinding wheel is adjusted with relation to the work and by which it is intermittently fed into the work.

A further object of my improvement is to provide means by which the grinding wheel may be easily and quickly adjusted so as to give practically the same length of bevel to all knives of equal thickness.

Heretofore it has been customary in machines of this kind to so mount the grinding wheel that it may have vertical adjustment with relation to the cutting edge of the knife, and it may also have independent horizontal adjustment. This necessitates a double adjustment of the wheel whenever it is desired to set it with relation to the work. There are serious disadvantages in practice resulting from this double adjustment, which will be apparent from the following considerations. If the wheel is directly over the blade and is moved by its vertical adjustment, it will of course grind the blade without any edge, that is, nearly square across the top. If the wheel is set to one side of the work and moved by its horizontal adjustment, it will produce a very long bevel on the side of the blade.

Any combination of vertical and horizontal adjustment between these two extremes will produce bevels of various shapes and it becomes extremely diflicultv in practice to keep the two adjustments so regulated with relation to each other that substantially the same shape of bevel will be produced on all the knives of a set belonging to one planer Specification of Letters Patent. Patented Aug; 11, 1914 Application filed. June15, 1912. Serial No. 703,988.

head andit is of course desirable to have them exactly alike. The required adjustment, owing to the wearing away of the grinding face of the wheel, will have to be brought frequently into use, especially where very thin grinding wheels are used.

It is therefore one of the objects of my invention to provide a mounting for the grinding wheel whereby practically the same shape of bevel will be given to successive blades, and the necessary adjustments will all be accomplished by one movement of the wheel.

A still further object of my invention is to provide means for automatically feeding the grinding wheel into the work by very small amounts at each reciprocation of the carriage and to so construct this feeding device that the rate of feeding the wheel forward when once set will not be disturbed by any subsequent adjustment toward and from the work.

With these and certain other objects in view which will appear later in the specification, my invention consists in the devices of the wheel set forth in the specification and pointed out in the claims, and the equivalents thereof.

In the drawings, Figure 1 is a perspective view of a saw grindingmachine with. my improvements attached; Fig. 2 is an end View of the machine with some of the working parts removed; Fig. 3 is a detached seetional view of part of the feeding mechanism; Fig. 4 is a detail of the rock shaft by which the feed mechanism is operated.

.The machine here illustrated is what is commonly known as a double machine, that is, provided with two grinding wheels oppositely placed to grind bevels on both sides of the knife edge. The wheels rotate in opposite directions so that one wheel removes the burr left by the other and produces a smooth, sharp edge, double beveled if desired.

Upon the frame 1 is mounted the reciprocating carriage 2 in which is secured the blade 3 to be ground. Grinding wheels 4: and 5 are revolubly mounted in diagonally disposed slides 6 and 7 carried by brackets 8 and 9. These brackets are pivotally mounted on the frame of the machine as at V 10 and 11, so that slides 6 and 7 may be tilted through various angles to raise and lower the grinding wheels 4: and 5. The

slides 6 and 7 enable the wheels to be fed toward or withdrawn from the work in a true radial direction with reference to the curve to which the bevel on the knife is be ing ground, this adjustment being distinguished from the ordinary independent vertical and horizontal adjustments previously described, in that the length of thebevel tilted and by which diagonally disposed slides 6 and 7 are moved toward and from the work, may, so far as the part of my invention just described is concerned, be of any suitable or approved type, but I prefer inpractice to employ the following devices as being especially well adapted to effect the desired adjustments and feed of the grinding wheels.

-Each of the slides 6 and 7 has a feed screw 12 (Fig. 8) carrying a gear 13 mounted in a suitable bearing to feed the slide backward and forward when the gear is rotated. The lower part of the gear projectsthrough a slot 14 in the bracket 9. Mounted in suitable bearings beneath the bracket 9 is a shaft 15 carrying a hand wheel 16 and pinion 17 engaging gear 13, and a ratchet wheel 18 adapted to be engaged by a pawl 19.

Pawl 19 is reciprocated by the vertical movement of a rod 20 which extends downward and is pivotally connected at its lower end to a radially adjustable crank arm 21. The rod 20 is provided with a telescopic extension 22 by which the rod may be lengthened or shortened to compensate for the tilt ing of bracket 9 in adjusting the machine. A set screw 23 is provided on the telescopic extension. This screw is loosened beforeithe bracket 9. is tilted, and is afterward tightened. v

The radially adjustable crank arm 21 is mounted on a cross-shaft 24 beneaththe reciprocating carriage 2. Shaft 24 is rocked at each reciprocation of the carriage'2 by means of the following device: Upon the shaft is mounted a trip arm 25, to the upper end of which is pivoted a weighted trigger 26 having its upper end beveled and adapted to be engaged by a tripping clamp 27 secured to the reciprocating carriage 2. The trip arm is adapted to be actuated in one direction only, the return movement ofthe carriage merely causing the trigger to swing to one side without moving the trip arm. A suitable fixed stop 28 is provided on the frame of the machine to limit the amount of movement of trip arm 25. An arm 29 is provided on the cross-shaft 24 and to the outer end of this arm is secured a tension sprin 30, the free end of which may be secure to any suitable stationary part of the machine. It is the function of thisspring to return trip arm 25 to its upright position after its displacement by the clamp 27 on the carriage.

-Movement of the carriage in one direction brings the tripping clamp into contact with thetrigger, partially rotating the cross-shaft 24, drawing down rod 20, actuating the pawl, ratchet wheel, pinion, and screw 12 to feed the grinding wheel radially. against the knife, the amount offeed at each operation of the carriage being regulated by adjusting the radial length of the adjustable M crank arm 21.

VVhile I have shown and described only one mechanism for feeding forward a single grinding wheel, it will be understood that in a double machine two sets of such feeding mechanism are provided, one set for each wheel. 4 o

By the means above described I have produced a simple and effective adjustment for the grinding wheels of knife grinding machines, whereby practically uniform length of bevelis attained, regardless of any ordinarydegree of wear of the wheel, and by which the forward movementof the wheel may be accomplished without necessitating a series of complicated adjustments.

Having described my invention, what I claim and desire to secure by Letters Patent, 1s:

1. In a knife grinding machine, com- A bination with the frame and the knife carriage, of a tiltable, pivotally mounted bracketcarried by the frame at an incline, a slide carried by said bracket, means for moving said slide lengthwise said bracket, a

flat grinding wheel carried by said slide and T lying in a plane parallel with the direction of movement of said slide. ,7

2. In a knife grinding machine, the combination with the frame and a reciprocating knife carriage, of a'tiltable bracket pivotally carried by said frame, a slide carried by said bracket and longitudinally movable thereon, a grinding wheel carried by said slide, and means connectlngsald kn fe carp 7 riage and said slide adapted to actuate said slide at each operation of said carriage.

3. In a knife grinding machine, the conibination with the frame and a reciprocating knife carriage, of a tiltable bracket pivotally mounted onv said frame, a slide carried by said bracket, a grinding wheel mounted on sald slide; and means for automatlcally moving sald slide, comprislng a feed screw carried by said bracket and engaging said slide,

gears adapted to actuate said feed screw, a ratchet wheel operating said gears,;a pawl and a reciprocating rod connected thereto, an extension device on said rod, a tripping device carried by the knife carriage, a crossshaft, an arm carried thereby and secured to said rod, and means carried by said cross,-

&

carried by the reciprocating carriage, and mechanism interposed between said screw and said tripping clamp and adapted to be 15 actuated by said clamp to intermittently turn the feed screw on said slide, for the purposes set forth.

In testimony whereof, I aifix my signature in presence of two witnesses.

. JOHN P. HEDSTROM.

Witnesses:

CHRISTINE A. BRAIDEL,

GEO. W. SMITH.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of IPatents, V Washington, D. G. 

